﻿/*
   Copyright 2013 Dmitry Bratus

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/
using Flower.Processing.Interruptions;
using Flower.Workflow;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Flower.Processing.Activities
{
    public class ExecuteAsync : Activity
    {
        internal Func<IContext, Task> Action { get; set; }

        private Task _runningTask;
        private Exception _runningTaskExcepton;

        public override bool IsBlocking
        {
            get { return false; }
        }

        public override Interruption Do(Processor processor)
        {
            if (_runningTask == null)
            {
                _runningTaskExcepton = null;
                _runningTask = 
                    Action(processor)
                        .ContinueWith(t => _runningTaskExcepton = t.Exception);

                return new Async { Task = _runningTask };
            }
            else
            {
                if (_runningTaskExcepton != null)
                {
                    throw _runningTaskExcepton;
                }

                ++processor.State.__ActivityPointer;
                return null;
            }
        }
    }
}
